Keep getting fire instead of smoke

[zZz]

So i made a smoke bomb composition and put it in a cardboard tube

No matter what i did , it kept getting too hot and burnt vigorously.

The composition was only :

12 gr sugar

12 gr paraffin

18 gr KNO3

And a pinch of bp to the end of the hole to give it enough activation energy

 

 

I did alot of these and almost all of them gave a good steady smoke at first and seconds later they caught on fire

I took a vid of one of them:

 

Any thoughts what's causing this?

[BetICouldMake1]

Have you tried just using 60% KNO3 40% Sugar?

[zZz]

Have you tried just using 60% KNO3 40% Sugar?

That's worse than this .

It acts like a rocket fuel

Paraffin actually slows the reaction and makes the smoke much denser

But it is not working lately

Something must went wrong

[Arthur]

Coloured smokes are often 25% fuel, 25% oxidiser and 50% dye, Sometimes they have a cooler chemical in there if needed (like a carbonate) to simply add cool particles to the gas stream. Often the shape of the outlet jet determines whether the flame inside is further oxidised by air from outside which then burns the smoke chemical.

 

The two likely things that will change from mix to mix are grain size and moisture content.

[greenlight]

I have had that happen before with the same mix.

I agree with Authur.

I found it is usually from lack of confinement. Oxygen gets in from the surrounding air which causes the mix to burn hotter and results in flame instead of the smoldering style burn rate which produces the smoke.

 

Only a small ejection hole(s) is needed so as not to allow oxygen in but the smoke out. The amount of ejection holes are chosen depending on the size of the device.

 

I usually use a thick walled closed carboard tube for these. The burning end being closed with a clay plug with three or four approx 1/8 inch diameter holes drilled in it a d fused through one. They are then filled with the mix and the other end just plugged with sand or other inert substance and taped.

Edited February 23, 2020 by greenlight

[zZz]

I have had that happen before with the same mix.

I agree with Authur.

I found it is usually from lack of confinement. Oxygen gets in from the surrounding air which causes the mix to burn hotter and results in flame instead of the smoldering style burn rate which produces the smoke.

 

Only a small ejection hole(s) is needed so as not to allow oxygen in but the smoke out. The amount of ejection holes are chosen depending on the size of the device.

 

I usually use a thick walled closed carboard tube for these. The burning end being closed with a clay plug with three or four approx 1/8 inch diameter holes drilled in it a d fused through one. They are then filled with the mix and the other end just plugged with sand or other inert substance and taped.

I thought of that , i covered the one hole with layersof aluminium foil and then taped it. I guess it wasn't enough . Plugging both sides with clay paste should work as you say? Edited February 23, 2020 by zZz

[zZz]

Yeah it was about exhaust all along , i plugged both exits with clay , opened a thin hole in the middle of that . And Eureka!

 

I got some intense and appealing smoke

 

Thanks for the support guys.

[greenlight]

I usually just plug one end with rammed bentonite clay, the other end doesnt have to withstand as much pressure and at the end of the burn it is minimal.

 

As long as you have adequate ejection holes so not too much pressure builds up to rupture the casing and at the same time doesnt allow oxygen to enter the device.

 

That extra atmospheric oxygen increases the burn rate and temperature and is extremely detrimental.

This comp seems to work best when it is underoxidized and burns in a smoldering fashion while confined.

[SeaMonkey]

Tech Ingredients has made video tutorials on

High Performance Smoke Devices:

 

Part 1

 

Part 2

 

Colored Smoke Devices

[zZz]

Tech Ingredients has made video tutorials on

High Performance Smoke Devices:

 

Part 1

 

Part 2

 

Colored Smoke Devices

I watched it before , so far the best tutorial on the yt